Conventional magnetic recording and reading devices, such as hard disk drives, optical drives, etc., are optimized for many parameters to run at various temperatures and operating conditions. The allowable temperatures and conditions may be visualized as windows of operation where the conditions and temperatures allow for consistently superior performance. These windows of operation have been getting smaller and smaller due to difficulties associated with areal density, such as a super-paramagnetic limit, size constraints, tolerances, process control limitations, etc. Operation of magnetic devices at cold temperatures, as an example, often requires additional write-ability of a magnetic recording head, and at higher temperatures is capable of writing in a manner which limits the thermal instability of a magnetic recording medium. In addition, surplus write current which is used for higher write-ability usually induces large thermal protrusion of write poles, which is equivalent to lower thermal fly-height control (TFC) power, which often results in poor head-disk interface (HDI) reliability, even at low temperatures.
Some attempts have been made at correcting for these issues. In one scheme to improve the write-ability of a magnetic recording head, a localized AC field is applied at adequate frequency to the medium using a spin torque oscillator (STO). This scheme is referred to as microwave-assisted magnetic recording (MAMR). However, it is very difficult to generate a localized AC field at microwave frequencies in a stable and reliable enough manner to assist high density magnetic recording in a thermally stable medium using a STO. Because an injected current density necessary to generate an appropriate AC field at microwave frequencies to assist high density magnetic recording is too high, such as 108-109 A/cm2, stable and reliable operation is often prevented using this scheme due to electro-migration.
Another attempt at correcting these issues relies on applying localized heat to or above the Curie temperature of the magnetic material of the media, such as higher than 300° C., within a nanosecond using a near field element and a laser, or just a laser. This scheme is referred to as thermally-assisted magnetic recording (TAM). However, such high temperatures are required for high density magnetic recording, but in these high temperatures the lubricant typically used to coat the medium may desorb from the surface of the medium, decompose, and possibly degrade. Furthermore, the diamond-like carbon (DLC) overcoat may degrade, inducing degradation of HDI related performance, such as head and medium wear, R/W performance, etc. Associated with these high temperatures, other effects, such as thermal protrusion of the write element and/or read element of the magnetic head, as well as transient elastic thermal distortion of the medium surface, have also been found to exacerbate the HDI stability, causing more degradation of HDI related reliability and of the R/W performance of the magnetic recording device.
MAMR and TAMR are referred to as energy assist recording processes, both of which promise improvements in the write-ability of a magnetic recording head.